Michelle Trudeau

Bears do it; bats do it. So do guinea pigs, dogs and humans. They all yawn. It's a common animal behavior, but one that is something of a mystery.

There's still no consensus on the purpose of a yawn, says Robert Provine, professor of psychology and neuroscience at the University of Maryland, Baltimore County. Provine has studied what he calls "yawn science" since the early 1980s, and he's published dozens of research articles on it. He says the simple yawn is not so simple.

When someone does something utterly selfless, you might think, oh, they're just a generous kind of soul. But new research suggests altruism may be hardwired in the brain. Reporter Michelle Trudeau has more.

Ever wonder why children can so easily figure out how to work the TV remote? Or why they "totally get" apps on your smartphone faster than you? It turns out that young children may be more open-minded than adults when it comes to solving problems.

Remember that famous line in the movie Jerry Maguire where Renee Zellweger says to Tom Cruise, "You had me at 'hello' "? Well it turns out there is some scientific evidence to back this up. People use voices to instantly judge people, researchers say.

Most research on memory loss in the elderly focuses on dementia, Alzheimer's disease or other brain diseases.

But neuroscientist Emily Rogalski from Northwestern University's Feinberg School of Medicine knew there is great variation in how good memory is in older people. Most have memory loss to varying degrees, but some have strong memories, even well into old age.

Miranda Kelly, a 14-year-old from Sykesville, Md., says she's been sleepwalking since she was 6 or 7. The first time, she says, "I woke up on the couch on a school day. And I'd gone to bed in my bed."

Since that first episode, Kelly now sleepwalks every couple of months. "I wake up in weird places, randomly. I have once woken up in the kitchen, and on the floor of the bathroom wrapped in my sheet," she says.